FreeBSD 7.0 fdisk issue during installation

Fri Nov 21 13:41:09 PST 2008

Hi Jerry,
Thank you for the swift and very thorough response.

If I understand you correctly, then I should only create 1 slice of the
entire disk (seeing as FreeBSD will be the only OS) using fdisk and then
partition the slice using bsdlabels from sysinstall?
Previously I was aiming for 5 slices, each of which had a single partition
as described below.

>From your explanation I take it that "slices" are what Windows refers to as
"Primary Partitions"?
If that's the case then I understand the behaviour I experienced.

Is it possible to make a slice non-bootable?
And would there be any benefits (less fragmentation, faster access time
etc.) in using slices rather than partitions to layout the harddrive or
should slices only be used to represent a physical harddrive?

Appreciate the clarification

Cheers
Jona

On Fri, Nov 21, 2008 at 8:55 PM, Jerry McAllister <jerrymc at msu.edu> wrote:

> On Fri, Nov 21, 2008 at 08:03:58PM +0100, Jonatan Evald Buus wrote:
>
> > Greetings,
> > I tried to install FreeBSD 7.0 on an old server earlier today and ran in
> to
> > a number of issues related to slicing and labeling the disk using fdisk.
> > The drive in the machine is a 40GB Seagate Barracude (ST34001A) installed
> as
> > a Secondary Master on the IDE bus using LBA.
> > The BIOS reports that the drive has 16 sectors pr block, but little else.
> >
> > When accessing fdisk during install, fdisk complains that the disk
> geometry
> > is invalid and sets it to the default geometry for 40GB:
> > Cylinders: 4865
> > Heads: 255
> > Sectors: 63
> > I've tried with the following configuration based on what was reported by
> > the BIOS:
> > Cylinders: 19150
> > Heads: 255
> > Sectors: 16
> > Looking in the manual:
> > http://www.seagate.com/support/disc/manuals/ata/cuda7200pm.pdf, Seagate
> is
> > specifying the following logical characteristic:
> > Cylinders: 16383
> > Read / Write heads: 16
> > Sectors pr track: 63
> > Which of these settings should be the correct one for the fdisk geometry?
>
> Let the system set it and just go with what it does.
> Geometry is virtual nowdays.   Except in some unusual situations
> (on IDE) Cylinders, heads and sectors most often do not mean what
> they used to.   The system drivers have it all figured out.  The
> important thing for you is the total number of blocks/sectors.
>
> If that doesn't work, you will have to do some diagnosis, but in
> about 10 out of 9 times, accepting how FreeBSD sets it is correct
> and works.
>
>
> > Additionally I encountered problems during installation if splitting the
> > disk into more than 4 slices. This would cause the following error to be
> > thrown during prior to the install files being copied (when sysinstall
> was
> > executing the newfs commands):
>
> You cannot have more than 4 slices.
> The system limits you to 4 slices, identified by numbers 1..4
>
> Once you divide in to slices, each can be further divided in to
> up to 8 partitions, although it is really 7 because partition 'c' has
> special meaning and is not really available to be a real partition.
> Partitions are identified with alpha letters a..h - with 'c' being
> used to identify the whole slice.
>
> You use fdisk to create the slices (and write the MBR and set
> the bootable flag).
>
> Then you use bsdlabel (formerly called disklabel) to create the
> partitions within a slice (plus write the slice boot block.
>
> Typically, you want to make partition 'a' be the root (/) filesystem
> and 'b' be swap space on a bootable system slice.   Some things assume
> these designations.
>
> Then you newfs partitions a, d, e, f, g, h or as many as you use.
> But don't touch c and don't newfs b if it is to be swap.
>
> ////jerry
>
> > "Error mounting /mnt/dev/X on /mnt/usr. No such file or directory"
> > Using only 4 slices seems to have solved this error, however I'd like the
> > disk layout to use 5 slices as follows:
> > / = 512MB
> > swap = 2048MB (the machine has 1024MB RAM)
> > /tmp = 512MB
> > /var = 2048MB
> > /usr = whatever remains
> > I noticed that when having 5 slices, the last slice (/usr) would be named
> X
> > rather than ad2s5 as I'd expect (the drive was detected as ad2).
> > Is this behaviour related to the error in any way?
> > Also, is the above disk layout good for a server intended to run both a
> web
> > server (Apache) and a database server (PostGreSQL) ?
> >
> > Finally after installation (using only 4 slices) the system will only
> boot
> > if the FreeBSD boot manager is used.
>
> That is probably because you have created what is referred to in the
> documentation as a "dangerously dedicated" disk.   You can make it
> work that way.  FreeBSD can handle it.   But other systems will not
> play nicely with it.
>
> > This in turn causes a 4 menu options, all of them named "FreeBSD" to
> appear
> > during startup despite only the / slice having been set as bootable in
> fdisk
> > which appears to be indicated by an "A" in the flag column.
>
> Again, because you tried to do it the wrong way.   You created 4 FreeBSD
> slices, probably each with an MBR and so the BIOS and the first MBR think
> they are all bootable.
>
>
> > Selecting the first menu item by pressing F1 will make the system boot as
> > expected.
> > It seems rather silly though to use a boot manager when FreeBSD is the
> only
> > operating system that is installed (and ever will be installed) on the
> > machine.
>
> You can put in the other non-boot manager block during installation
> if you want and it will only boot FreeBSD.   But, something is needed.
> I forget what they call it in the sysinstall screen, but you might just
> as well put in the FreeBSD boot manager (MBR).
>
> > If the FreeBSD boot manager is not used however and only the MBR is set
> > during installation, the system will fail at startup with error "Invalid
> > Partition Table".
> > Is this because the harddrive is installed as the Secondary Master on the
> > IDE bus?
>
> No, it is because you did not create any partition table (with bsdlabel).
>
> ////jerry
>
> >
> > Appreciate any input on this
> >
> > Cheers
> > Jona
> > _______________________________________________
> > freebsd-questions at freebsd.org mailing list
> > http://lists.freebsd.org/mailman/listinfo/freebsd-questions
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> freebsd-questions-unsubscribe at freebsd.org"
>

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